The present invention relates to agricultural toolbars, and more particularly, it relates to agricultural toolbars which are flexible, permitting outboard wings to independently adjust vertically to follow variations in ground contour. The present invention is described in the context of an applicator for liquid fertilizer, although the structure and hydraulic operating circuit for the disclosed toolbar has broader application than liquid fertilizer applicators.
Agricultural toolbars, particularly toolbars which are designed to apply liquid fertilizer, are typically designed so that the mounting bars on which the individual applicator units are fixed, are held or supported at a desired distance above the ground by adjustable depth gauging wheels. This is because it is highly desirable that fertilizer be placed at a constant depth beneath the surface of the soil so that the fertilizer is available to the plant for the various stages of development and growth of the plant.
Up to a width of ten feet or so, rigid toolbars are useful because the variations in ground contour over a ten-foot span transverse of the direction of travel of the tractor, typically would not encounter a substantial variation such as might result in non-uniform application of liquid fertilizer. For greater widths, however, agricultural toolbars are typically supported with their own gauge wheels, and they include a center section and right and left wings which are hinged to the center section so that each wing may independently follow the contour of the ground. Toolbars which have wings capable of hinging about horizontal axes extending parallel to the direction of travel are called xe2x80x9cflexiblexe2x80x9d toolbars. The term refers to the independent vertical movement or flexing of the wings relative to the center section. Even wider toolbars, such as the one in connection with which the present invention is illustrated, may have each wing divided into an inner wing section and an outer wing section which fold or hinge relative to each other about a vertical axis (in the field use position) which reduces the overall height of the implement during transport and provides even more compact, and thus more maneuverable arrangement for road travel. It is desirable that a section of the toolbar have a width no greater than eighteen feet in order to accommodate variations in ground contour most commonly encountered.
Modern farming practices have made it desirable to use large toolbars (that is, toolbars having a greater width in the field use position) because of the increase in the size of farms as well as a desire to reduce operating expense and the amount of time spent in the field. Modern farming practices also make it desirable that a toolbar for applying liquid fertilizer be highly adaptable or adjustable in the sense that it accommodate placement of individual applicators at a wide range of spacings. The applicator units on a fertilizer applicator are normally spaced at a constant distance relative to one another. However, the distance between adjacent applicator units will vary according to farming practices and according to the spacing of crop rows. Planting and fertilizer practices create a demand that a toolbar for liquid fertilizer application be capable of mounting the ground-engaging tools (i.e., applicator units) at a wide range of lateral spacing. The row spacings of particular interest are twenty, twenty-two, thirty, thirty-six, thirty-eight and forty inches. In addition, the present toolbar is capable of supporting a side-dress application for a thirty-inch row spacing with fertilizer placement at six inches on either side of the center of a row.
Moreover, in the past, toolbars for applying liquid fertilizer have been operated with a wide variety of controls and set-up structures, including manual, electrical and hydraulic. The operator is required not only to learn the control system for a particular implement, but he is also required in many situations not only to operate the control system for the toolbar, but also to maneuver the tractor and observe the correct spacing relative to existing crops or to fertilizer which already has been applied in adjacent swaths. It has therefore become desirable that the control system for liquid fertilizer applicators be simplified from the standpoint of operation, particularly during field use and maneuvers. Further, it is desired to avoid manual operations and procedures by the farmer/operator outside of the tractor cab, either in preparing the applicator for transport or in field use. When all operations can be accomplished from the operator""s position on the tractor, simplicity and safety are both enhanced.
The illustrated toolbar has a center section and left and right wings. Each wing, in turn, has an inner wing section and an outer wing section. The inner wing sections pivot vertically about respective horizontal axes located at the outboard ends of the center section. The outer wing sections pivot horizontally relative to their associated inner wing sections about axes located at the outboard end of the associated inner wing section. These hinge axes are vertical when the toolbar is located in the field use position. Obviously, the hinge axes of the outer wing sections take various orientations relative to the vertical and the horizontal as the inner wing sections rotate relative to the horizontal.
More recently, larger fertilizer applicators of this type having hinged wings typically include a gauge wheel mounted to the outboard end of each wing. Liquid fertilizer applicator units conventionally include a leading rippled coulter for parting the soil and forming a narrow furrow, followed by an applicator assembly including a is delivery tube for delivering the liquid fertilizer in the furrow. A thin knife may be mounted behind the coulter if desired. The operating depth of the coulter is thus determined by the height of the toolbar to which it is affixed. For the center section, the operating depth is determined by the height of the toolbar of the center section which is adjusted relative to the primary support wheels for the main frame of the unit. The operating depth of the applicator units fixed to the wings is determined by the height of the center section (since the inboard end of each wing is mounted to the center section frame) and the height of the associated wing depth gauge wheel.
The center section and inner wing sections each are formed into double-rank toolbars. By this, it is meant that each frame section has a forward mounting bar and a rear mounting bar. Forward and rear mounting bars in a double-rank toolbar are typically made into a rigid frame by intermediate frame sections extending in the direction of travel. Such an arrangement interferes with the desired universal adjustability in mounting the fertilizer applicator units (i.e., tools) with a wide variety of lateral settings. The structure of the present toolbar does accommodate a wide variety of lateral settings of the tools, including those spacings of greater interest to the farmer/operator. Instrumental in achieving universal adjustability of lateral spacing of applicator units is an unique hinge structure located between the center section and each associated inner wing section. This hinge, while providing a hinge structure for both the forward mounting bars and the rear mounting bars of the inner wing sections, offsets the hinge mounting structure relative to the associated mounting bars in such a manner that for virtually every lateral position in the region of the hinge, either the forward bar or rear mounting bar will accommodate the mounting of an applicator unit. In the past, the use of conventional hinges has made it impossible or impractical to mount the applicator units to the toolbar frame with universal adjustability of spacing yet maintaining uniform spacing between adjacent tools.
The present invention also provides for the application of load or ballast (i.e., a downward force) to the wings during operation by, in effect, transferring weight from the center section (which carries the substantial weight of the mainframe supporting the liquid fertilizer and storage tank) to the wings through the use of a constant pressure hydraulic circuit. The hydraulic circuit is engaged when the fertilizer applicator is in the field use position, and induces a constant downward force on each wing, independent of the downward force on the other wing and independent of the weight being borne by the center section. The downward force applied to each wing is also independent of the positions of the wings with respect to one another and with respect to the center section. That is, the hydraulic circuit is designed so that if one wing flexes downwardly from the horizontal, the constant pressure (and downward force) is maintained, and if the wing flexes upwardly from the horizontal, the constant pressure (and downward force) is also maintained on both wings.
A constant downward force on the wings is desirable because the weight of the wings themselves is not great enough to maintain the applicators in the desired depth setting across the entire width of the toolbar under all soil conditions. For one thing, although the wings are designed to have sufficient strength, including a margin of safety, for all conditions encountered in use, the wings are nevertheless folded upwardly for transport so that excess weight or ballast on the wings is undesirable in the transport configuration. In conditions of dry or packed soil, the resistance to penetration of the coulter typically found on a liquid fertilizer applicator unit, may not penetrate to the desired depth. In this condition, the wing will raise; that is, the gauge wheel on the wing will rise above the ground because a substantial portion of the weight will be borne by the coulters. When a coulter is operating at a depth less than the desired depth, the delivery tube which deposits liquid fertilizer behind the coulter, is raised above the desired depth so that the fertilizer is not deposited at the intended depth.
Thus, according to the present invention, the hydraulic cylinders which raise and lower the inner wings (called xe2x80x9cinner wing fold cylindersxe2x80x9d) are operated under constant hydraulic pressure when the toolbars are placed in a field work position and then forced down for fertilizer application. This permits each wing section to continue to adjust to ground contour independently of the other wing section and the center section, while applying a substantially constant downward force on each wing section so that the coulters will penetrate even compacted, hard soil, and the applicator units will operate to deliver the liquid fertilizer consistently to the desired depth.
The hydraulic control circuit for the present invention operates in four primary is modes or cycles: (1) Unfold, (2) Work or Field Use, (3) End of Row Turn, and (4) Fold. All functions are accomplished by the operation of two main valves, a work valve and a transport valve, both located in the tractor cab for convenience and safe access. Assuming that the toolbar is in a horizontal position, having undergone an Unfold cycle from the transport position, the operator places the work hydraulic valve in a detent position. This position causes a main or center lift cylinder to retract, lowering the center frame section to operating (i.e., work or field use) position. The wings are then forced downwardly because the inner wing fold cylinders are extended. When the inner wing fold cylinders are fully extended, they are placed in a constant hydraulic pressure operating mode. That is, hydraulic pressure and flow from the tractor hydraulic pump is fed through a reducing/relieving valve and coupled to the inner wing fold cylinders to place them in the extended position with a constant hydraulic pressure in the butt or cylinder end. This applies a constant downward force on the wings, transferring weight from the center frame section to the wings, while permitting the wings independently to accommodate variations in the terrain. The constant downward force on the wings permits the applicator tools to operate at the desired depth, set by the wing gauge wheels, as the implement is drawn forward by the tractor. Operation in the Work mode may continue as the operator desires since the lever operating the directional Work valve is in a stable, detented position.
At the end of a row, the operator places the Work valve in an End of Row Turn mode. In this mode, the main lift cylinder is extended to raise the center section frame, and the inner wing fold cylinders are retracted a limited amount, disengaging all ground tools and raising them to the End of Row Turn position. A limit switch is actuated as the wings are placed in a position which is substantially horizontal, but turned up slightly. Thus, the fertilizer applicator tools are raised from the soil, permitting the operator to effect an End of Row turn.
After the operator has completed the desired fertilizer application, and he wishes to move the implement to another location, the implement is placed in a transport configuration. To achieve this, the operator actuates the directional Transport valve to the Fold position. The hydraulic system causes the main lift cylinder to extend, raising the center section frame. In addition, the hydraulic system causes the outer wing fold cylinders to retract, folding the outer wing sections rearwardly about vertical axes. That is, the toolbars of the outer wing sections remain in the same general plane as the toolbars of the adjacent inner wing section. The inner wing sections are then folded over center by retraction of the inner wing fold cylinders until the wings rest on a wing support mounted to the center section frame. When the wings come to rest on the wing support, the inner wing sections extend inwardly, forming a delta shape with the center section frame; and the outer wing sections extend generally horizontally in a rearward direction. This reduces the overall height of the implement in the transport mode, and enhances the safety of the implement.
To place the implement from the transport position to the unfold position, the operator places the Transport valve in a second or unfold position. When the Transport valve is placed in the unfold position, the inner wing fold cylinders extend. The wings rotate outwardly relative to their associated hinge connections to the center section frame, so that the inner wing sections rotate downwardly. The inner wing sections achieve the desired horizontal position and actuate the limit switch to stop the unfolding of the inner wing sections. The outer wing sections are then rotated to extend outwardly, aligning with their associated inner wing sections. This unfold sequence reduces the overall height of the implement and reduces the possibility of interference from obstacles during the Unfold cycle.
Thus, the entire operation of the implement is controlled from the operator""s position on the tractor using two tractor hydraulic selective control valves. This allows the operator to concentrate on tractor placement, tractor speed and row alignment, rather than manual procedures or distracting operations for the implement, while providing a winged fertilizer applicator implement having both inner wing sections and outer wing sections for increased operational width while reducing the overall transport height to manageable dimensions.
Other features and advantages of the present invention will be apparent to persons skilled in the art of the following detailed description of a preferred embodiment accompanied by the attached drawing, wherein identical reference numerals refer to like parts in the various views.